In phase transfer catalysis a reactant in a liquid organic phase ordinarily is reacted with a second reactant in another phase, usually aqueous, the reaction being catalyzed by a so-called phase transfer catalyst. The phase transfer catalyst acts to solubilize or extract inorganic and organic ions, in the form of ion pairs, into the organic phase. Without such a catalyst the desired reaction would be slow or might not occur at all.
U.S. Pat. No. 4,290,977 (Hucks et al.) shows the preparation of neutral phosphoric acid esters by the method of phase interface condensation. Phosphorus oxychloride, for example, is reacted with phenol in a mixture of water and toluene which also contains sodium hydroxide. The reaction is carried out at 25.degree.-30.degree. C. for a period of 20 minutes. The yield of "pure product" is said to be virtually quantitative. A stoichiometric excess of phenolic reactant is required in the reaction.
U.S. Pat. No. 3,836,608 (Franko-Filipasic et al.) shows the reaction of phosphonitrilic chloride polymers with an alcohol or alkoxide to produce a partially chlorinated ester. The partially chlorinated ester then is heated to form a condensed polymeric system by eliminating alkyl halide while forming P--O--P bonds. The preferred temp for the latter reaction is 130.degree. to 220.degree. C. The use of linear polymers in the reaction is preferred. The preferred temperature range for the reaction is 130.degree.-220.degree. C. All of the illustrative examples of the process show the reaction of sodium propoxide with a stoichiometric excess of phosphonitrilic chloride.
The reaction of sodium 4-nitrophenate with dimethoxythiophosphoryl chloride is shown to be catalyzed efficiently by a mixture of N-methylimidazole and a quaternary salt (TBAB) at page 94 of "Phase Transfer Catalysis in Organic Synthesis", Weber et al., Springer-Verlag, 1977. Also, at page 256 of this same text there is shown the "normally difficult nucleophilic displacement on hexachlorocyclotriphosphazene" facilitated by 18-crown-6 ether. "Crown ethers" are sometimes used as phase transfer catalysts.
"Phase Transfer Catalysis", Dehmlow et al., Verlag Chemie, 1980, at page 77, shows the reaction of a dialkyl phosphite with carbon tetrachloride and an alcohol in 50% aqueous sodium hydroxide to give a trialkyl phosphate. Benzyltriethylammonium chloride (TEBA) is used as a catalyst. The reaction is illustrated by the following equation ##STR1## The reaction of dichlorophosphazene trimer with sodium trifluoroethoxide is shown at page 152 of "Phosphorus-Nitrogen Compounds", Allcock, Academic Press, New York (1972).